Orange Is the New Black star Laverne Cox is a person true to her word.

Shortly after receiving her first Emmy nomination on Thursday morning (Cox is the first openly transgender person to get one), she told PEOPLE that she planned to celebrate in shimmying style: by attending Justin Timberlake's Mastercard Priceless Access concert at Hammerstein Ballroom in N.Y.C.

"I'm going to dance, jump around and sing Justin Timberlake songs all night long," she said.

And that's exactly what she did!

According to an onlooker, Cox "put everyone to shame" with her rocking out. While other celebrities in her section, including Meredith Vieira and Timberlake's former 'NSYNC bandmate Joey Fatone, bopped their heads to the music, Cox "was up on her feet breaking out some amazing moves," the onlooker says. "She sang along and seemed to be having the best time of anyone there."

Two classic Timberlake tunes that seemed to be favorites of the TV star? His 2002 Grammy-nominated hit "Like I Love You" and the breakup jam "Cry Me a River," which got a roaring reaction from the rest of the crowd as well.

Cox, who plays Sophia Burset on the hit Netflix show, is joined by friends and castmates Natasha Lyonne and Uzo Aduba in the outstanding guest actress in a comedy series category.

Though making more history with a win will be on her mind, it's her wardrobe choice for TV's big night that is consuming her energy.

"It's a ton of pressure," she says. "I'm hoping to be wearing some couture something. But I want to get my body tight. I should head to the gym and do the rest of my interviews on the elliptical!

Cool how time does not go by .. But it does when my kid stands next to a brother and she is almost as tall as him lol pic.twitter.com/bKnPEAzlbM